Switches in the form of load interrupter switches nowadays have a modular design and consist of pole cassettes, which are usually assembled from two plastic shells. Connection elements are connected to one another via a switching contact during closing of the switch, the switching contact having a stationary and a movable contact element formed from current-conducting copper parts and having a planar contact area, wherein the movable contact element, over the course of the closing process, pivots out of an open position into a closed position.
The mutually facing contact areas which are aligned parallel to one another in the process slide bearing against one another, for example, into the closed position. The copper parts of the connection elements are fixedly clamped in grooves provided between the plastic shells.
This design, owing to the component part tolerances, results in a system with multiple overdeterminacies, which firstly result in positional inaccuracies of the component parts with respect to one another and secondly mean that fitting requires considerable force. This has a negative influence on the opening and closing behavior of the switch, for example asymmetrical striking of the arc, which then can result in severe fusing of the contact elements in the event of a short circuit. In addition, the grooves in the plastic shells, which grooves are fixed in terms of their dimensions given a switch size, each require an identical thickness of the copper parts and therefore always the same amount of copper, even if the switch is rated for different rated current intensities, which has a direct effect on the production costs since the costs of the copper make up a large proportion of the component costs.
The problem of the positional inaccuracies can be solved by highly precise geometries and dimensions of the component parts including housing parts, with the disadvantage that increased production costs need to be accepted, in particular in the case of switches designed for low currents.